The invention concerns a processing machine for flat workpieces, especially for producing bent edges on sheet parts and/or for cutting or stamping of workpieces formed from sheet metal with a horizontal, and in particular, a strip-like workpiece holder and with a processing tool as well as with a hold-down device subdivided into individual segments arranged near the processing tool for clamping the workpiece on the workpiece holder. The segments are arranged in a row alongside one another in the direction of the orientation of the workpiece holder and a processing line, and in particular a bending line, and are movably and fixably mounted in this direction, whereby they are electively separable or couplable with an adjusting drive extending basically over the length of the hold-down device.
A processing machine of this general type is known from EP-0 258 204 B1. The shifting of individual segments of the hold-down device here serves to take undercuts arising from sheet metal processing into consideration and to be able to remove the hold-own device from the workpiece despite such undercuts. At the same time, the movable segments are individually adjustable by means of an adjusting rod in connection with the known processing machine, whereby each segment has its own clamp coupling for connection with this adjusting rod. In the coupled position, the segments are carried along and moreover displace the additional segments lying in front of the coupled segment viewed in the direction of adjustment.
Thus, a great expenditure is necessary for being able to selectively adjust individual segments or groups of segments, because each segment requires its own clamp coupling with an associated activation. To be able to selectively connect the segments with the adjusting rod or a carrier, they have recesses running transversely to the adjusting rod in which in any given case a clamping element can be moved. Each clamping element must be loaded in the clamping seat by two clamping springs whose force must be cancelled out by adjusting cylinders. These adjusting cylinders require appropriate bore holes for a pressure medium. A pilot valve is necessary for control in any given case which for its part needs an appropriate connection with a control. The individual segments must thus also have a minimum dimension in order to be able to accommodate the coupling which consists of clamping elements and activating elements in any given case.